Caterpillar says its new 90-metric-ton
(198,000-lb) 390D L hydraulic excavator,
which replaces the 385C L, incorporates a
refined design that results in a more productive, durable and efficient machine
that can handle jobs in a range of aggregates, coal and hard rock mining applications. Powering the new 390D L is the
18.1-liter (1,104 in3) C18 ACERT diesel
engine, rated at 523 net hp (390 kW).
Refinements in the C18’s crankcase, cylinder heads and proprietary MEUI (Mechanical Electronic Unit Injector) fuel system
provide enhanced engine performance and
durability, while design enhancements in
the implement hydraulic system allow the
390D L to deliver greater digging and lifting forces than its predecessor. Main relief
pressure in the implement circuits has
been increased to 5,080 psi (35,000 kPa),
up nearly 10% from the 385C. This
increase in operating pressure, combined
with larger-diameter hydraulic cylinders,
results in a 9% boost in digging-arm and
bucket breakout forces for the general-purpose and reach front-end configurations,
and a 7% increase for the mass excavation
configuration. In addition, lifting capacity
over the end is increased by 9%, and over-
the-side capacity is up nearly 20%—the
result of stronger hydraulics and a heavier
counterweight. Also new in the implement
hydraulic circuits are electrically controlled
regeneration valves, which assure rapid,
positive response from the boom and digging-arm cylinders, while significantly
improving overall hydraulic efficiency. The
resulting benefits include quicker cycle
times and estimated fuel savings of more
than 2%.
An improved undercarriage for the
390D L features redesigned links that
operate with lower stress, forged idlers for
improved durability and heavy-duty track
rollers and carrier rollers. In addition, the
recoil spring has been lengthened, giving
the recoil mechanism greater impact- absorbing capability to protect the under-
carriage system from shock loads. To
accommodate the higher digging and lifting forces generated by the 390D L, the
carbody is fabricated with thicker reinforcing plates at critical locations. Complementing this change are thicker plates at
the boom-foot mounting in the upper
frame, as well as thicker reinforcing plates
in the rails and bottom pan to accommodate the heavier counterweight and
increased swing-torque.
To facilitate easier, environmentally
sound routine maintenance, the 390D L is
equipped with protected, valve-controlled
fluid-drain ports and self-contained hoses
for fuel, coolant and lubricant systems.
Easy-to-change spin-on filters are used in
the fuel and lubricant systems, and pressurized fluid-sampling ports (in all pressurized-fluid circuits) assure reliable fluid samples. An electronic warning system alerts
the operator if the air filter or hydraulic filter is approaching restriction limits. The
Electronic Power Control (EPC) has been
relocated from the cab to the air-cleaner
compartment, allowing the cab floor to be
washed without risk of damage to the EPC.
For further reliability, the EPC and its electrical terminals are weatherproof.
www.cat.com
As featured in Womp 2011 Vol 03 - www.womp-int.com
